However why did they swarm when they did? Just get overcrowded late in the game, or is there a problem (mites?) that makes them act odd? -Mike I haven't found any sign of mites yet. The colony started out in the spring as a split. It was doing quite well, by late august it had filled two shallow supers. Interesting enough the day I went to pull the honey was the day I found the swarm. They took enough of the honey with them that I didn't dare remove any of the remaining honey from the old colony.